Ok, my car will overheat only when i'm moving in 5th gear, or 4th for while like 5 minutes.. The temperature warning needle goes up to 220* then 240*, then i get nervous and slow down, and it cools down. I can drive in traffic 50 mph and slower all day long but once i get going about 60 for a few minutes, that darn needle starts wandering up! I have a 180* Thermostat, have a NEW Aluminum Radiator (Milodan) new Fan belts, and of course a new radiator cap. Should i run without a thermostat and see what happens? What is going on here? I really have no idea

------------------
--Steve S-- 84 Trans Am 305 (cough)LG4(cough), 5 speed, Flowmaster 80 series, otherwise an emissions restricted slow 150 hp(chilton rating) 240 torquer that needs RELEASE!!!!

P.S. Daily Driver

 

Do you have the air dam under the car still? This is very important too cooling, especially at higher speeds. If so I'd look to a faulty gage. Get a scanner and read what the coolant temp sensor is saying.

------------------
Rob P
89RSconvtZZ4TPI
Edelbrock Hi-Flow Intake
SLP Dual Cold Air Intake
1 5/8" Headers
Semi-Siamesed Runners
MSD6AL/relocated MAT/ AdjFPR/IROC frnt@rear swaybar/wonderbar/steeringbox/alum drvshaft/ Alston SFC/3:23posi disc rear/MAC LCA/H.Adams Panhard Rod/KYB struts/ shocks/
92Z28convt5spd
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

Still overheats, in VA, in January??

Damn! You in a heap o' trouble, boy!

------------------
FORMULA 350 TK
Southern California 3rd Generation F-Body Organization©

 

Thanks Tom.....

I just looked at the coolant, still green with a yellow brown, foam tint. I'm running Bar's Stop Leak in there, but i dunno. Please God don't let it be a Head Gasket....Yah i have the air dam, ($$crap$$)..

------------------
--Steve S-- 84 Trans Am 305 (cough)LG4(cough), 5 speed, Flowmaster 80 series, otherwise an emissions restricted slow 150 hp(chilton rating) 240 torquer that needs RELEASE!!!!

P.S. Daily Driver

 

I'd check my gauge. And also check to see if you have any crap in front of your radiator. Sometimes a bag or someother junk gets in there. My friends supra looked like it had a birds nest in between the radiator and a/c condensor.

 

Someone else told me to check the gauge too, guess i'll do that before i mess with the stuff in the engine compartment first. I'll check for junk too...

------------------
--Steve S-- 84 Trans Am 305 (cough)LG4(cough), 5 speed, Flowmaster 80 series, otherwise an emissions restricted slow 150 hp(chilton rating) 240 torquer that needs RELEASE!!!!

P.S. Daily Driver

 

Don't you just love GM's cooling set up on these cars? The 83Z got hot (same high temps as yours and quick, too). The important air dam (the one that bolts up directly under the radiator was missing). We replaced it and still had problems. After putting in a new thermostat, hoses and water pump, we still had the problem. We noticed that the fan did not start until the temp. was above the 195 degree thermostat, but comes on only when the water coming out of the radiator is already hotter than the thermostat is set to open at. We bought one of the cheap little fan switches that turn the fan on at 170 degrees (Jeg's, Advance Auto, etc.) and wired it into the switch circuit and took care of the problem. In my opinion the coolant coming out of the radiator out to be cooler than the thermostat opening temp (195) or it'll never run at 195. My 81Z never gets more than 5 degrees above the 180 thermostat, but then there's no fancy electronic stuff to cause problems, either.

 

see if the air dam is still there. Its only 30 bucks thru gm. I know this because a tow truck took mine off. Then she overheated just like yours! I went thru everything else that your doing all it was the air damn located under radiator. good luck

------------------
88 camaro rs convetible 92 rims / flowmaster/ hypertech chip/ 3.73 gears/tbi spacer/open elemnt/hollowed cat/shift kit corvette servo/k&n filters/holley tbi unit/nox squeeze/future mods 350 with 400 crank/sub frame conectors

 

ok lets get started, i have the same problem still too but at all speeds just not that bad. ok you said the air dam is there good, everything else sonds good to but....change the 180 to a 160 (for now) also something noone else said have you changed the water pump? on smallblock chevy water pumps the impellers inside the pumps are well known for falling off and you'll never know it. no rattles, no squeakes, no leaks . just a lot of overheating try getting a replacement pump from your local parts store, also make sure if there is no fitting screw on top of the water pump for the heater core that the new one doesn't either(trust me no matter what anyone says in pats store!) do this and you should be fine also check the fans as soon as this starts and see if the water is boiling. and make sure the new radiator cap is stock pressure for the radiator, too high could overheat the car!

------------------
1989 firebird formula

Mods: converted from T.B.I. to a carburator 305 to a 350. Flowmater exhaust,hedman shortie hedders,202 heads,350 horse cam,bored.40 over, Edlebrock torker2 intake.

Future mods 400 performer rpm intake (polished) and 600 edlebrock carb, comp roller cam, and way better heads. orpossibly a 383 stroker?

 

also if the head gasket is blown you'll most likely (not always ) have water in the oil. no power to speak of, and hard to start at times.

------------------
1989 firebird formula

Mods: converted from T.B.I. to a carburator 305 to a 350. Flowmater exhaust,hedman shortie hedders,202 heads,350 horse cam,bored.40 over, Edlebrock torker2 intake.

Future mods 400 performer rpm intake (polished) and 600 edlebrock carb, comp roller cam, and way better heads. orpossibly a 383 stroker?

 

I have confirmed it isn't the Head gasket, cuz i got good power, did a burn-out last night , my boss (who is a Master Mechanic) mentioned something about the impeller, but said he only sees that like once every 7 years, and only happens 1% of the time. So it probably isn't that, but not ruled out totally. I was reading about emissions and my THERMAC inlet could be sticking open (just a wild hunch) so replace that with a Open element Air Cleaner. Replacing Passenger side Valve Cover tonight so i'll take a look at the EGR valve... I'm going to reflush the system tomorrow and see whats up...Thanks for all your help, i'll tell u guys what i find.

------------------
--Steve S-- 84 Trans Am 305 (cough)LG4(cough), 5 speed, Flowmaster 80 series, otherwise an emissions restricted slow 150 hp(chilton rating) 240 torquer that needs RELEASE!!!!

P.S. Daily Driver

 

I have exactly the same problem!! I have an 85 Trans Am (Mint Cond.) with 45K original miles. My car's temp will climb up to 240 and bounce back and fourth between 240 and 220 when I am on the highway but as soon as I drive in town the temp drops. I change my coolant every year. My water pump is fine. There is no scale whatsoever in my radiator. The first thing I did was change the thermostat, but it had no effect. I had a full tune up done and replaced a faulty battery and Alternator and the problem got worse. The engine would get even hotter!! I have taken this car to the dealership and they have no idea! I was beginning to suspect the temperature guage sensor but after reading this entire topic I went out and did some detective work and I discovered that my car did not have the air dam underneath. Someone must have removed it or somehow it was torn off. I took off the radiator shroud to check to see if there was some debris between the A/C condensor and the radiator. Whoa!! I could not believe the crap that collected between there. My radiator is 70% plugged with leaves, hair, and other crap. I am still in the process of cleaning this mess up so I cant yet tell you if this has resolved my issue, but I would be very suprised if I still have this problem.

Many Thanks to you all very much for your clues!!

This would be a tough problem to diagnose because its kind of unique to this era of Camaro's and Firebirds because of the front end. It has to pick up air from under the car to cool. In my opinion as an engineer,I feel it is a rather poor design on GM's part especially since proper cooling is reliant on a cheap $30 dollar piece of plastic that can be torn off by a parking stall curb stop or by hitting a small animal.

 

Another common problem is the lower radiator hose. There is supposed to be a spring in there to keep it from collapsing, but they go anywhere from getting eaten by rust, to being sucked in by the water pump, or being removed by an unknowing owner.
Easy to check, either squeeze the hose by hand or start up the car and rev the engine up past 2000, the hose will usually collapse if theres no spring.

 

Felt a spring, bought a air dam before but returned it, looked like it was on my car, but i want to double check myself... What is the part number?

------------------
--Steve S-- 84 Trans Am 305 (cough)LG4(cough), 5 speed, Flowmaster 80 series, otherwise an emissions restricted slow 150 hp(chilton rating) 240 torquer that needs RELEASE!!!!

P.S. Daily Driver

 

Too correct my previous statement. I have NO AIR DAM! I was @ the junkyard and saw a Firebird (it had caught fire) that had the air dam. AHA! this is what it looks like! So i try to take it off, but don't have the right sized socket adaptor. So i'll go back tommorrow and put it on. Then i'm going to test it on the Interstate and tell you guys how it went.

------------------
Whenever I "Fix" my car, something always "breaks"
1984 Trans Am 305 LG4, 5 speed Auto
RPO codes point to Recaro version, want to put a 500 Cadillac in but money is on a vacation...
Mods

More coming...
P.S. Daily Driver

 

Well i tested it yesterday. I am glad to say that it did the trick. Even stayed cool around 90 mph (just like it should!) Thanks everyone for all your help. Now i can get out of this town!

------------------
--Steve S--
1984 Trans Am 305 LG4, 5 speed Auto
RPO codes point to Recaro version
Daily Driver, Flowmaster 80 Series

[This message has been edited by 84TransAm (edited January 22, 2001).]

 

A happy ending! Yeah! I guess some people think of the front ground FX as the air dam and not the part way under the car.
Glad it's fixed!

------------------
Rob P
89RSconvtZZ4TPI
Edelbrock Hi-Flow Intake
SLP Dual Cold Air Intake
1 5/8" Headers
Semi-Siamesed Runners
MSD6AL/relocated MAT/ AdjFPR/IROC frnt@rear swaybar/wonderbar/steeringbox/alum drvshaft/ Alston SFC/3:23posi disc rear/MAC LCA/H.Adams Panhard Rod/KYB struts/ shocks/
92Z28convt5spd
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

Glad to hear it's fixed. Your not the first, and probably not the last either, with that one!

------------------
"So many Mustangs, so little time..."
ICON Motorsports